import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';

function Square(props) {
	return (	
	<button className = "square" onClick = {props.onClick}>
		{props.value}
	</button>
	);
}


class Board extends React.Component {

	renderSquare(i) {
    return (
      <Square
        value={this.props.squares[i]}
        onClick={() => this.props.onClick(i)}
      />
    );
  }

	render() {
    return (
      <div>
        <div className="board-row">
          {this.renderSquare(0)}
          {this.renderSquare(1)}
          {this.renderSquare(2)}
        </div>
        <div className="board-row">
          {this.renderSquare(3)}
          {this.renderSquare(4)}
          {this.renderSquare(5)}
        </div>
        <div className="board-row">
          {this.renderSquare(6)}
          {this.renderSquare(7)}
          {this.renderSquare(8)}
        </div>
      </div>
    );
  }
}
class Game extends React.Component {
	constructor(props) {
		super(props);
		this.state = {
			history: [{
				squares: Array(9).fill(null)
				}],
				stepNumber: 0,
			xIsNext: true
		}
	}
	
	handleClick(i) {
		const history = this.state.history.slice(0,this.state.stepNumber+1);
		const current = history[history.length - 1];
		const squares = current.squares.slice();
		if (calculateWinner(squares) || squares[i]) {
			return;
		}
		squares[i] = this.state.xIsNext ? '●' : '○';
		this.setState({
			history: history.concat([{
					squares: squares
			}]),
			stepNumber: history.length,
			xIsNext: !this.state.xIsNext,
		});
	}
	jumpTo(step){
		this.setState({
			stepNumber:step,
			xIsNext:(step%2) === 0
		});
		
	}
	render() {
		const history = this.state.history;
		const current = history[this.state.stepNumber];
		const winner = calculateWinner(current.squares);
		
		const moves = history.map((step,move) => {
				const desc = move ? 'Go to move #'+move : 'Go to game start';
				return(
					<li key={move}>
						<button onClick={() => this.jumpTo(move)}>{desc}</button>
					</li>
				);
		});
		
		let status;
		if (winner) {
			status = "Winner" + winner;
		} else {
			status = 'Next player: ' + (this.state.xIsNext ? '●' : '○');
		}

		return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={(i) => this.handleClick(i)}
          />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <ol>{moves}}</ol>
        </div>
      </div>
    );
	}
}

// ========================================

ReactDOM.render( <
	Game / > ,
	document.getElementById('root')
);


function calculateWinner(squares) {

	const lines = [
		[0, 1, 2],
		[3, 4, 5],
		[6, 7, 8],
		[0, 3, 6],
		[1, 4, 7],
		[2, 5, 8],
		[0, 4, 8],
		[2, 4, 6],
	];

	for (let i = 0; i < lines.length; i++) {
		const [a, b, c] = lines[i];
		if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {
			return squares[a];
		}
	}
	return null;
}